45钢表面激光熔覆NiCrBSi涂层的组织和摩擦磨损性能

Microstructure and Tribological Properties of NiCrBSi Laser Cladding on 45 Steel Substrate

采用激光熔覆技术在45钢表面制备N iC rBS i合金涂层,利用EPM A,SEM和TEM分析了激光熔覆层的微观组织,测试了激光熔覆层在不同环境气氛压力下的摩擦磨损性能。结果表明:激光熔覆层由熔覆区(CZ)、结合区(BZ)和基底热影响区(HAZ)三个区域组成。熔覆区的组织是在-γN i树枝晶和-γN i+N i3B共晶的基体上分布着细小的C rB颗粒和C r7C3树枝晶,结合区是基底材料和熔覆材料的混熔区,呈定向凝固特征,基底热影响区为针状马氏体组织。激光熔覆层的摩擦磨损性能与环境气氛压力密切相关,随环境气氛压力的降低,摩擦系数增大,磨损量减少。

Laser cladding of NiCrBSi powders on 45 steel substrate was conducted, and microstructure of the laser cladding were analyzed using EPMA, SEM and TEM. The friction and wear properties of the laser cladding were examined under different atmospheric pressures. The results showed that the laser cladding could be divided into three regions, the cladding, bonding and heat affected zones. In the cladding zone （CZ）, fine CrB particles and Cr7C3 dendrites were distributed in matrix of the γ-Ni dendrites and the eutectics consisting of γ-Ni and Ni3B. The bonding zone （BZ） was a mixture of melted 45 steel and Ni-base alloy, and displayed directional crystallization. The heat affected zone （HAZ） had an acicular martensitic structure. The friction and wear properties of the laser clad layer were closely related to the atmosphere pressure. When the atmosphere pressure was lowered, the friction coefficient was increased, and the wear loss of mass was reduced.